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Water/Wastewater Conveyance
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Diaphragm valves are glandless valves that use a flexible elastomeric diaphragm (a flexible disk) as the closing member and in addition affect an external seal. They are well suited to service in applications where tight, accurate closure is important. The tight seal is effective whether the fluid is a gas or a liquid. This tight closure feature makes these valves useful in vacuum applications. Diaphragm valves operate similarly to globe valves and are usually multi-turn in operation; they are available as weir type and full bore. A common application of diaphragm valves in water or wastewater operations is to control fluid to an elevated tank.
Membrane Fouling, Cleaning, and Sanitization
Published in Maik W. Jornitz, Theodore H. Meltzer, Sterile Filtration, 2020
Maik W. Jornitz, Theodore H. Meltzer
The art is to admit steam into the housing surrounding the filter, to raise the temperature of the cartridge in advance of steam penetration and thus avoid condensation of the steam. Furthermore, air pockets within the filter system have to be avoided. Therefore one should always open the vent and drain valves when steam is admitted, to drain condensate and vent the air through the bleed valves. Autoclaving a filter system, whether a disposable device or a filter housing, usually is done with pre- and postvacuum cycles to vent any air within the filter equipment and to dry the filter afterward. When in-line steaming, once steam without condensate droplets leaves these valves, one should gradually open the outlet side valve to achieve steam flow through the filter. Usually the valve bore diameter is smaller than the inlet pipework diameter, so pressure builds up slowly within the filter housing and heats it. The cartridge and its membrane start heating up, and air and condensate are removed. A clear steam flow will appear at the valve outlets as soon as the appropriate temperature is reached. At this point the filter should have reached 100°C, and eventually condensate or liquid within the membrane matrix evaporates. When the downstream valve is gradually opened, the steam will flow through the opened pores of the membrane. The upstream and downstream valves have to be correctly adjusted to maintain the required steam pressure and sufficient differential pressure to achieve a continuous flow of steam through the entire membrane matrix. Furthermore, the differential pressure should not exceed the manufacturer’s specifications. For this reason, most filter systems should be equipped with pressure transducers on the up- and downstream sides. Membrane (diaphragm) valves are the valves of choice due to their cleanability and finer adjustment. Once the pressures have been adjusted, one can close the drain and vent valves, but not completely, so steam can still penetrate through them.
Study of flow and heat transfer characteristics around a flat plate located between two symmetrical cylinders
Published in Science and Technology for the Built Environment, 2021
Y. Deng, G. Z. Yin, L. Wang, S. D. Zhou, S. H. Zhai, G. N. Xi
Figure 4 presents the open-loop fluid test bench (Zhou et al. 2017) and the hardware equipment for the particle image velocimetry (PIV) system (Biegowski, Paprota, and Sulisz 2020). The hardware of the PIV system includes a laser, cooler, synchronous controller, power supply, camera, and computer. The test bench includes the upper and lower head tank, water pump, and rectifying, contraction, test, and recovery sections. Experiments were conducted under stable operating conditions of equipment. At the beginning, water is driven to the upper head tank by the water pump. The upper head tank can stabilize the water flow. Then water flows into the rectifying section through the water pipe and the flow velocity can be controlled by the diaphragm valve. There are two sizes of honeycomb in the rectifying section, which ensure the uniformity and stability of the flow. Finally, water flows into the lower head tank again through the recovery section.
Experimental Study on Wake Development in a Three-cylinder Model within a Tunnel in Transitional Flow
Published in Heat Transfer Engineering, 2018
Shaodong Zhou, Jie Zhou, Liang Zhao, Guannan Xi
Experiments were carried out in an open-loop, recirculating water tunnel that operated at steady-state conditions. As shown in Figure 1, the recirculation water tunnel is mainly consisted of upper head tank, rectifying section, contraction section, test section, recovery section and lower head tank, pump and so on. Firstly, the water as the medium is driven to the upper head tank with a pump. The purpose of adoption of the upper head tank is to reduce flow instability produced from impingement. Then the flow velocity is controlled by a diaphragm valve that can realize to coarse and fine control. A hexagonal honeycomb having a pore size of 30 mm, a length of 1200 mm, width of 900 mm and height of 300 mm was placed in the rectifying section. The shape of the contraction section adopted a cubic curve and the shrinkage ratio is 3:1. A relative smaller shrinkage ratio can ensure a better steady-state of flow. The transparent acrylic-plate that can be penetrated by the laser was used in fabricating the test section. A specific size of the test section has length of 1200 mm, width of 300 mm and height of 300 mm. similarly, the recovery section also use the acrylic-plate and has length of 2400 mm, width of 300 mm and high of 300 mm. The connections between sections used a method of flange. Finally, the water flows into the lower head tank, and then flow driven by gravity into the tank with the pump, to complete a cycle.
Use of membranes for the treatment and reuse of water from the pre-cooling system of chicken carcasses
Published in Environmental Technology, 2021
Cristiane M. Marchesi, Marshall Paliga, Carolina E. D. Oro, Rogerio M. Dallago, Guilherme Zin, Marco Di Luccio, J. Vladimir Oliveira, Marcus V. Tres
The pre-filtered water was stored in a refrigerated 150 L stainless steel feed tank and pumped through the filtration modules. The pressure was controlled using a diaphragm valve and a manometer in the retentate stream. The permeation assays were carried out in total recycle mode and at 200 and 400 kPa of transmembrane pressure. The flow rate was fixed at 3400 L h−1. Samples of permeate were collected during 1 min, for flux measurement. Then, 200 mL samples were collected, frozen and kept under −18 ± 1°C for further physical–chemical and microbiological assays. The operational temperature was maintained at 16°C.